Cartridges, especially filter cartridges for treating drinking water are known. On the one hand, these are cartridges that are used in gravity-operated water filter systems, especially for household purposes. In this case, the cartridge is arranged in a hopper into which water is filled. Through an inlet, the water flows into the cartridge at an upper side thereof and leaves the bottom of the cartridge at a lower outlet. For other applications, in particular in gastronomy and for vending machines for preparing hot drinks such as coffee and tea, cartridges are known which are either inserted into a device or which have connections adapted to be connected into a drinking water conduit.
In Central Europe, such replaceable cartridges are mainly used to reduce the hardness of water, especially the carbonate hardness of drinking water. For this purpose, the cartridge is equipped with an ion-exchange material, mostly a weakly acidic resin which is disposed in a chamber in form of a granulated material. The use of such cartridges is especially intended to improve the taste of hot drinks, in particular it is possible to reduce the haziness in tea which is typical for hard water.
However, the generic cartridges for water treatment may furthermore have the task of removing suspended particles, germs, heavy metals, etc. from the water.
The cartridges are usually designed as a disposable system, i.e. they are discarded after the intended multiple use or supplied for reuse in a deposit system.
European patent EP 2094611 B1 (BWT International Trading Ltd.) discloses a method and a device for enriching water with magnesium ions. In particular, this patent discloses a cartridge for a gravity-operated household water filter, which contains a weakly acidic ion-exchange material which is partially loaded with hydrogen ions and partially with magnesium ions. This enables in a particularly simple manner to enrich the water with magnesium. At the same time, the acidification of the drinking water is reduced by the employed ion-exchange material loaded with magnesium ions.